Backup Exec SR 2010 & 2011: incremental vs. differential backup

[Daria9000]

Just seeking verificantion here.  I'm used to using the term "differential" to define a backup that consists of all files changed or added since the most recent full backup and "incremental" to refer to backups that backup only files added or changed on the day the backup is run.

Symantec, however, seems to use "incremental changes" to refer to differential backups.  Are the incremental recovery points indeed really differential recovery points?

In other words, say I create a full backup (recovery point set) on Jan. 1 and select the "incremental" option for backups on Jan. 2-30.  Then I need/want to restore my drive to the way it looked on Jan. 20.  If the recovery points are differential, all I should need to do is restore the manual base and the incremental recovery point created on Jan. 20.  If they are incremental (by above definition), I would need to restore the manual base and every recovery point up to and including the Jan. 20 point.  (And, yes, I do realize that restoring a differential backup will not restore any files deleted between the base and the date of the differential.)

[Ken_Putnam]

Both DIFF and INCR check the archive but (or change time if you use modified time)

The difference is that INCR resets the archive bit and DIFF does not.  So INCR grabs any changes since the last FULL or INCR, while DIFF grabs any changes since the last FULL (or INCR, which is why it is not recommended to mix INCR/DIFF)

For DR recovery, yes, with DIFF you need only the last FULL and the last DIFF, while with INCR you need to restore the last full and every INCR, in sequence.

And you are correct, any files deleted after the last full will be present after a recovery using either method

Symantec has a way around this, tho.  Synthetic Backups.  They compare the last full or synthetic backup and basically run an INCR, but the result is exactly as if you had run a new full.  (of course the latest full/synthetic backup must be on-line and available when the next synthetic job runs)

[Daria9000]

I'm afraid i don't completely understand your reply. 

When I run a backup and select the "incremental" option, is Backup Exec performing a differential or an incremental backup?  Or put another way, if I have a base backup and multiple incrementals, as defined by Backup Exec, what do I need to do to restore to a certain time: restore the base and all the backup points until the desired date or just the base and the backup point on said date.

[pkh]

If you are using full + incremental backups, then you need to restore the full backup plus all the incremental backups.  For example, you do a full backup on Sun and incemental backups on Mon, Tue, .., Fri nights.  If you want to restore your system back to Wed., then you need to restore the Sun. full backup, followed by the Mon. incremental, then the Tue incremental and then the Wed. incremental.

Synthetic backups are a feature of ADBO which is a payable option of BE.  You can read about its features in the Admin Guide.  If you are not using ADBO, then you can ignore what Ken said about synthetic backups.

[Daria9000]

Thank you.  I didn't even know there was such an animal as an ADBO option ....

OK, so far so good.  A Full Restore requires the base plus all incrementals up to the date of the restore.  That's standard and I get it.

Now, when one is managing disk space and selects the delete option, there's a choice to "delete all but first and last". Does that mean that, the consolidation results in a backup that contains the full base plus any files added/changed in the last incremental - but nothing that was added in between?

In other words, let's say I do a full on Monday, incrementals on Tues-Sat.  On Wednesday I create a new file (so it gets picked up by the Wed. incremental) but make no changes so it isn't picked up by the Thurs-Sat incrementals.  I consolidate the recovery points for the set.  Now I need to restore the partition as of Sat.  Will that file created on Wed. be restored?  In a system with differential backups, it would be (as long as I didn't delete it between Thurs. & Sat.).  In a system with incrementals only, it wouldn't. But why offer a consolidation option that will omit x number of files?

[pkh]

I think you are talking about BESR/SSR and not BE.  These are two different products and what Ken and I said only applies to BE and not BESR.  BESR/SSR has its own forum and you should post your questions in that forum, not here.